Effect of indomethacin on CO2-induced hyperaemia (CO2-response) in the rabbit brain

It was studied in rabbits whether indomethacin, a prostaglandin-synthesis inhibitor, influences cerebral hyperaemia induced by inhalation of carbon dioxide (CO2-response). The aim of this experiment was to show whether prostaglandins are involved in the regulation of cerebral vascular tone. The animals were repeatedly ventilated with a CO2-room air mixture before and after the injection of indomethacin solution. Regional cerebral blood flow in one hemisphere was continously measured using a thermo-clearance method. In 10 out of 13 rabbits no effect of indomethacin on the CO2 response could be observed. In the other 3 animals a reduction of the CO2-response only occurred in the 15-45 minutes interval after the indomethacin injection. The authors, however, do not exclude the possibility of this reduction being an artefact. The reasons are discussed.